~66 million years agoReputable source · 2 sourcesWell documented
The Day the Mesozoic Died: The Chicxulub Impact
On the timeline · around ~66 million years ago · After the Dinosaurs
What happened
A city-sized asteroid slammed into what is now the Yucatán Peninsula of Mexico, carving out the vast Chicxulub crater. The impact triggered wildfires, tsunamis and a global 'impact winter' as debris blotted out the Sun. Around three-quarters of all species — including every non-bird dinosaur — died out.
Why it matters
This mass extinction ended the 165-million-year age of dinosaurs and reset the course of life on Earth.
How we know
In 1980 the physicist Luis Alvarez and colleagues found a worldwide layer of iridium — rare on Earth but common in asteroids — at the boundary, and proposed an impact; the matching Chicxulub crater was later identified beneath Mexico.
Sources
- Natural History Museum. How an asteroid ended the age of the dinosaurs · Reputable source
- Natural History Museum. What killed the dinosaurs? · Reputable source
Related timelines
- Evolution of Life on Earth → — The fifth great mass extinction